Gmail Watcher is a Google Mail Reader and Notifier for Ubuntu which made by Owais Lone. It support multi account, realtime notifications, and preferences sync through UbuntuOne.

Not like thunderbird, Gmail Watcher only provides read email function without providing mail reply functionality. When I try to use it, Gmail Watcher will give NotifyOSD notifications not more than 1 minute after email received by your account.

Gmail Watcher give NotifyOSD notification

Gmail Watcher FeaturesHere some features you can find in Gmail Watcher taken from its official page.

Multiple Accounts

Google Apps support

Secure password storage using Gnome-Keyring

Themable unread emails page

Preferences sync using U1

Install Gmail Watcher via PPA in Ubuntu
Here following to install Gmail Watcher in Ubuntu PPA, other ways you can download the source here and do manual installation.

sudo add-apt-repository ppa:loneowais/gmailwatcher.dev

sudo apt-get update

sudo apt-get install gmailwatcher

After the installation process was finish, run Gmail Watcher for the first time from Applications > Internet > GmailWatcher, then fill some required settings. Here some screenshot of Gmail Watcher taken from my desk.